Opto-electrical model of a single-junction photovoltaic cell using Monte Carlo methods

In the context of the development of solar photovoltaics for global energy production, it remains essential to clearly identify performance limitations. The present article revisits the interpretations of photovoltaic cell performance by introducing a path-integral formulation of the current. The case of a single p-n junction cell operating in low injection conditions is examined as a proof of concept. The total current is calculated by implementing two different algorithms, which exhibit two viewpoints for analyzing the physics involved. The first one describes random walks on a reverse path space, back to the source of charge carriers. The second one describes random walks on a direct path space, starting from the source. Both algorithms are validated against an analytical solution. A Monte Carlo algorithm is also proposed for directly determining the voltage at the maximum power point without requiring the entire current-voltage curve. The calculation of a spectral-spatial internal quantum efficiency, combined with a statistical analysis of the random paths, demonstrates the relevance of this approach for interpreting the involved physics. Numerous benefits are anticipated from our advancements in Monte Carlo techniques: enhanced physics representations, insensitivity of computation time to the dimension of the integration domain, and to the geometrical complexity at all scales.